Additive manufacturing finds more applications every day, especially in medical devices, ranging from models, tools, to implants. The fabricated parts have to withstand the mechanical loading applied during their lifetime. Hence, optimization of process parameters must be performed to reach the best performance of the manufactured part with the given polymer. A fractional design of experiments is performed with the ARBURG plastic freeforming using a medical-grade poly (methyl methacrylate) to improve the overall mechanical performance. Tensile specimens are produced, tested, and the impact of different parameter settings is analyzed to identify the factors with the highest impact on the mechanical performance. Based on the results, further parameter optimization is performed. A direct correlation between the density and the tensile properties of the printed parts is observed. Further, an influence of the processing pressure resulting from changes in the processing temperature is detected. Optimization for good mechanical performance is performed, and a relation between the filling of the parts, the nozzle temperature, and the discharge pressure on to the tensile properties is found. This investigation reveals that shrinkage due to changes in temperature and pressure has an essential role in determining the tensile properties of specimens produced by ARBURG plastic freeforming.